Conventionally, the countermeasure to lessen the vibrations and noises of the disk drive have been mainly focused on the structure of the disk drive, concretely, the addition of vibration-absorbing materials and noise-preventing materials. The upper limit value of the disk rotation speed of the disk device is predetermined on the disk drive side. In a case where the vibrations are sensed by a vibration sensor or a servo error signal with the upper limit value as the maximum rotation speed, the disk rotation speed is automatically slowed down. However, except such a special case, the disk drive operates at the maximum rotation speed corresponding to the upper limit value, so that the rotation of the disk brings about relatively large vibrations and noises. Further, each user feels the noise uncomfortably or not with his or her own sense. Hence, the upper limit value of the disk rotation might be made lower than actually required. Moreover, the conventional disk drive has no means of changing the upper limit value of the disk rotation speed on the user's side.
However, in response to the recent request for speeding up the processing of data and lowering the cost, the disk drive has been devised to speed up the disk rotation speed and reduce the components in number. For this purpose, the change of hardware such as an electric circuit like a motor and a structure has been carried out. For each change is required a new countermeasure for preventing the vibrations and noises.
Moreover, the user cannot practically change the upper limit value of the disk rotation speed of the disk drive because the user has to design complicated software based on technical knowledge and give a special instruction to the disk drive.